Polyphase transformer



S. HORELICK.

POLYPHASE TRANSFORMER. APPLICATION mm my 28. 1921.

Patented Aug. 8, 1922.

n avwa utor 5 rd M -irre 'efiiciency, but also unbalances and distorts UNITED STATES PATENT OFFICE.

SAMUEL HOBELICK, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO PITTSBURGH TRANSFORMER COMPANY, A CORPORATION OF PENNSYLVANIA.

POLYPHASE TRANSFORMER.

T 0 all w/wm it may concern:

Be it known that l, SAMUEL HoRsLicK, a citizen of the United States, residing at Pittsburgh, in the county ofAllegheny and State of Pennsylvania, have invented certain new and useful Improvements in Polyphase Transformers; of which the following 15 a specification.

This invention relates to polyphase trans formers and particularly to the form of the core and its relationship to the polyphase windings. y I

The polyphase transformer is generally preferable to the' use ofia"plurality of single phase transformers by reas'on of the economy in cost of material and the cost of manufacture. In some forms of "polyphase transformers, particularly'those of the simple'st types, the parts are not symmetrical throughout in their relationship; and in operation the unsymmetrical distribution ofmagnetic flu xfcauses an unbalanced or ar actioii' which not only lessens the theresultin'g electromotive forces'and currents induced in the secondary windings and results 'inwide variations in operating exciting current, with attendant greater variations in instantaneous exciting current and in the' various m'agneticcirc'uits and One object of my invention is to produce a polyphase transformer of asimple construction and capable OfbBiil economically manufacturedand in which't e parts are so related as to give quite a symmetrical relationship and operation throughout the cycle of operation. I accomplish this by providing a'c'onstruction which will give quite a symmetrical relationship of the paths for the magnetic flux so that in operation any irregular condition or relationship of the interactions issubstantially avoided. Also by my improved construction all of the windings are capable of being symmetri- Cally; similarly and uniformly su ported and also similarly and equally venti ated in all parts. -The construction as a whole is also economical in the amount of material required in the polyphase core and coils.

Another object of my invention is to produce a olyphase transformer which will have big efficiency and low and symmetri cally distributed exciting current, both nor- Specification of Letters Patent.

Patented Aug. 8, 1922.

inal operating and instantaneous, on all magnetic circuits or phases, and thls results from the relationship of the parts andtheir form of construction. 1

My invention will be understood by ref erence to the accompanying dra'win illu'strating one embodiment thereof, 't ej'particu lar embodiment illustrating a: three phase transformer.

Fig.1 is a front elevation of the polyphase transformer illustrating the polyphase core and coils;,Fi .'2"is'a plan view thereof with the core 5 own :in a central section; Fig. 3 is a diagram showing the outlines of the core and indicating. generally the paths of the magnetic flu); at {a 'particular instant, and Figs; 4, 5 and .6 are similar diagrams indicating the general paths of the magnetic flux at different instants.

Figs. 1 and 2 show three windings 10 10 and 10 each comprising the primary an secondary coils of one of the three phases, their connections being such as may be desired in any particular instance. "The windings have laminated central cores 11, 11? and 11 respectively. At each end of the transformer is a leg 12 and 12 at the out side of the end windings and in the plane of the laminae of the portions 11; 11" and 11 within the windings. The portions above referred to are joined to and complete their magnetic circuit through an up er portion 13 and a lower portion 13? which are made up of laminae and extend lengthwise in the plane of the laminae of the other portions, as shown in Fig. 1. It will of course he understood that the core may be built up of laminae of such length and shape as to suit the particular preference of the designer as regards economy in cutting the sheet material and in the assembly of the parts to form the complete core as above described. Ventilating spaces 14 may be provided in the core.

The primary and secondary coils are of general elliptical or oval form, as shown in Fig. 2; and the central core of each of the coils and likewise the end legs and the upper and lower connecting portions are deep in the direction perpendicular to the plane of the laminae compared with the width of the core between the interior side surfaces of a coil; and the central core of each of the coils has a general outline conforming to the ect e y w l e fis iei t y,

interior surface of the coils by tapering the ends. The core within each of the coils is therefore in close proximity toithe coils throughout and preferably has a' general elliptical form conforming in outline gen= erally thereto, with notches as strewn forming ventilating spaces. Also there is only a small part ofthe coils not enclosed by the iron, resulting in 'ivingnquite a complete low reluctance pat for the flux around nearlyall portions of the coils. The continuous; and gradually curre shape of the coils and"the avoidance of ahrupt bends, gives a very uniform distri hution of the magneticIflux created, by;tlie coils and; ermits the efl'ectiyeandefiicient use thereo'g Thev portions offl'the core within the cpils bein similarly shaped and in close proximity E1 the interior surface of the coils, results intheir carrying the flux .heca se h a serve thQ QIII fQIII1 flQUX distribution asset p b the sc IM? ill-. uti z t sp within the cpilsi The ,:c0l'ls.tll l( l lgl0l l results id e h armonioiisiriterac icn between the coils and theeore and irregular interactions which; tend to reduce e c iency are overcome. Figs, bfilild dai in af general way ,the paths of the magnetielineso' force at certain instants. In F igrBQthe in: in portion lif is assumed have thevihai imum value, at vyhlch time; the fflugrinv portions 11 and I1? willthoreticall have one-half the value and Pam downwardly through these portions and upwardly ithrough portio'n, 11. The flux ll take the'paths as rndicatetl approximate y. in Fig' 3 indirection and amoun't. In Fig, .4 the flux throu h the portion 11" tithe flux through is assumed to be zero an the ortion 11 will havethe same direction as efore, liut .less in amount. The flux through portion 11? will have thesaine dire:- tionas before, but in, reateramount, ,The paths'of the flux and t eir amounts are inclica-ted inageneral way in Fig. 4.

In-Fig. 5 the tin; through'the' portion 11 is assumed to have maximum, value, at which time the flux through portions 11 and 11 Will have half the maximum 'valuefand' be inithe ,opposite direction giving the paths of the flux',,a nd'their amounts as indicated in Fig 5. In'Fig fi theflux throu h portion 11 assumed to be zero, at which time the flux through portion 11 will be less than the m aximum andthe flux through portion l1 will are the same yalue, but in the opposite direction, thegeneral condition being indicated in Fig. 6,

Of course additional instants of operation could beconsidercd out the above are sufticint to showthc adrantageof my inrention in this respect. That is, it will be seen that the length of the paths taken by the magnetic flux is at all instants generally the same and in cases e here the length of the path is sometimes longer. the amount of flux passing through the longer path is of coinparatively small amount. Consequently the reluctance opposing the small amount of flux taking the longer path causes no appreciable unhalancing. Thus with my invention a greatly improrecl condition is obtained due to the close approach to symmetrically 'related conditions at all times. (.onsequenlly the flux harmonizes quite well with the induced magneto electromotire forces and distortion of the Wave forms is reduced to a minimum.

It will be noted that the magnetic fluxvof each phase has two paths in parallel at every instant of the c 'cle, thus reducing core loss and normal and instantancous exciting cur-- rent, and also at the same tinie attaining these advantages with a minimum amount of corematerial. v p

lso by use of my invention it will be seen that the upper and lower portions of the core and the ,end portions of the core carry only about one-half of the magnetic flux of the portions of the core \vithnrthe coils \vhich permits the size of the outside portions to be made considerably narrower than would be necessary in case they were required to carry the same amount of flux as the portions within the coils. The cross sectio n; of each enc l p orti0 n is such as to permit free. anduninterrupted flow of approximately one-half of the magnetism from the core of an adjacent coil. In ractice thisis attained with best economy making the cross sectional area of each end portion approximately one-half of the c'rosssectional area of the portion of the core within a coil, as shown in Fig. 2 of the drawings. It is also evidentthat all of thecoils are similarly situated with relation to the core which permits them all to besimilarly supported and similarly and equally ventilated, thus giving a uniform and symmetrical construction throughout Since the portions of the core outside the coils are required to carry only one-half of the niagnetic flu x within the coils and since the core is d ee J in a direction perpendicular to-the plane o the laminae, the portions of the core outside the coils may he made comparatively r arronp These narrow portions also improve the efliciency and operating charaarteristics of the transformer in that the path of the flux is shortened closely around the coils and in passing through the narrow )ort ions occupies quite completely and uniformly the whole of the cross sections 0r the portions through which the flux is passing at any instant.

The advantages resulting from my invention in improved operating characteristics and efliciency also permit the portions of the (0H3 within the coils to be made smaller than in prior constructions which permits the size of the coils tobe made correspondingly smaller with resulting economy in cost of copper, while still obtaining greatlyim proved results in efficiency and operation.

Although I have-described my invention with reference to a three-phase transformer, it is evidentthat it may be applied to polyphase transformers of a different number of phases and the connections oil the coils may of course be such asto suitthe particular requirements without departing from the scope of my invention.

I claim I I 1. A polyphase transformer comprising, coils side by side in the 'same plane, and a laminated transformer core-ihaving all of its lamina:'in-planes-parallel to each other a'ndv having a lengthwise portion extending along-each end of the coils respectively, and having intermediate po'rti'onsaconnect;

ing said lengthwise portions and extending through the coils, and also? having-enda-pou tionsllocated at theoutside of-the'iend coils .respectively' and connecting the said length.- wise portionsthemagnetism created; in the said intermediate portions zOf' the core all passing in said parallel lamina :fllld. the cross section of each of said end portions being approximately} ha'lffthat of one of said intermediate portions, the said intermediate and end portions having greater depth of said parallel laminae in a direction perpendicular to the plane of the coils than width, and the interior dimension of said coils in a direction perpendicular to the plane of the coils being greater than the dimension in a direction parallel to their plane.

2. A polyphase transformer comprising coils side by side in the same plane, the interior surfaces of said coils having gradually and continuously curved end ortions, and a laminated transformer core aving a lengthwise portion extending along each end of the coils respectively, intermediate portions connecting said lengthwise portions and extending through the coils, and end portions located at the outside of the end coils respectively and connecting the said lengthwise portions, the said core comprising laminae all of which are parallel to the plane of the coils, the said intermediate portions having greater depth of said parallel laminae in a direction perpendicular to the plane of the coils than width, the interior dimension of said coils in a direction perpendicular to the plane of the coils being greater than the dimension in a direction parallel to their plane, the width of said lengthwise portions and of said end portions of the core bein narrow compared with the width of said intermediate ortions and the cross section of each of said end portions being ap proximately half that of one of said intermediate portions, q and the magnetism created in said-intermediate portions of the core all passing in said parallel laminae.

3. A polyphase transformer comprising coils side by side in the same plane, the interior/surfaces ofsaid coils having a gradual and continuous curvature through out, and'a laminated transformer core hav ing.all of'its1laminae in planes parallel to each other and having-a lengthwise p0r tionextending along each end of the coils respectively, and 7 having intermediate portionsf connecting said lengthwise portions and extending through the coils, and-also havingendsportions locatedlat the outside of' the end coils respectively and connecting'the said lengthwise portions, the cross section ofreach of =said endportions being approximately-halfthat of Zone of said intermediatetportions, and the magnetism cn'eated in-the said intermediate portions .of theh core: all: passing-= in said parallel a a:- i--4.-; A polyphase transformer comprising coils side-"b asidehin the same plane, and ailaminate transformer core having a lengthwiserportionextending along each end of the coils respectively, and having intermediate;.mportions connecting' said lengthwise portions and extending through the coils and also having end portions located at the outside of the end coils respectively and connecting the said lengthwise portions, the said intermediate portions of the core comprising laminae parallel to the plane of the coils and having greater depth of said parallel laminae in a direction perpendicular to the ,plane of the coils than width, and the interior dimension of said coils in a direction perpendicular to the plane of said coils being greater than the dimension in a direction parallel to their plane, said coils being of general elliptical form.

5. A. polyphase transformer comprising coils side by side in the same plane, and a laminated transformer core having a lengthwise portion extending along each end of the coils respectively, and having intermediate portions connecting said lengthwise portions and extending through the coils and also having end portions located at the outside of the end coils respectively and connecting the said lengthwise portions, the said intermediate portions of the core comprising laminae parallel to the plane of the coils and having greater depth of said parallel laminae in a direction perpendicular to the plane of the coils than width, the interior dimension of said coils in a direction perpendicular to the plane of the coils being greater than the dimension in a direction parallel to their plane, and the interior surface of the coils having gradually and continuously curved end portions, and the bentkal portion 50f each core conforming in. generaloutline-to the inner surface of each of=the coils respectively.

6. A polyphase' transformer feompi'isi'ng coils. side by sidewin the-5si1ine"plitne, :ifncl a laminated traii sforiner cofie having "a lengthwise portion #ex-tending along each end of the coils-.srespotlvelv; end having intermediate orti'dns rim'ofinectin 5 1 said lengthwise portion 1; eicteridin'g ele y: each the coils and also l-ia ving en'ol nortlons hi Catfifl lit the outsi'de' of 'tlie end coilswesp'eetivel} and connecting the sliikrlfiengtlnfiSe poirtins the said intermediate and end [h tions of the (tore-comprising"lajniinaeperal- 161 to the -plafie'-of" thfcoils and having greater depth of said parallel lamina inii (liieetion; per endicular to'thh p lei ne of the coils than Width the ihte'rior Himeneio'n of said eons in e dir'eetionfitpendi'ol ilar we the plane of the cells belliggreaivee than the fliihnslon hb a direcuiompatilelwo theifi plane, and the interior surface of thew 011% having rad'uall' hhd"0fitlnhliiis1y our-ted end pbiti 'ns,-en' the sitid"'ifiteriiiediate pertioiis 'cbnforn'iihg' in =gehe1el outline 'to' the inner eurface of eaeh' of the mile" repee f -ivg fly i Grai n's Hr-w it:

7. A polyp'liese tmn's formeweohxprisihg passing through the coils conforming to the interior surface of each-of the coils respectirely.

A polypha-se transformer comprising coils side by side and-having their axes suhstantiall; )arallel to each other in the ewe plane, wind It leminzited "core having all its liiminte'ili'planes parallel to each other fiinel haiing a p'ortion within each o'fthe coils iespe: tivel',":1n end portion outside-eachof the endcoils', and a. portion joining the ends of each of said portions vespettive'ly; eaxEh of said coils having ah inter'i'orsur fa'c'e otgeneral elliptical form, andz the generulmontour of the portions of the core passing through the coils conforr nilrg to-llre lnterioiysurfaceof each of the coils respectii elyi sA Uen HOR-ELIGK. 

